Anode for vacuum discharge-tubes.



C. F. W. BATES.

ANODE FOR VACUUM DISCHARGE TUBES.

APPLICATION FILED AUG- IT. I915.

Patented Feb. 6, 1917.

a NT @FFJIQE.

CHARLES FREDERICK WILLIAM BATES, 0F CLEVELAND, OHIO, ASSIGNOB, OF ONE-HALF T0 CHARLES L. GEBAUEB, OF CLEVELAND, OHIO.

ANOIDE ron VACUUM DISCHARGE-TUBES.

Specification of Letters Patent.

Patented Feet, 1191?.

To all whom it may concern:

Be it known that 1, CHARLES FREDERICK WILLIAM BATES, a citizen of the United States, residing at Cleveland, in the county of Cu ahoga and State 'of Ohio, have invente a certain new and useful Improve ment in Anodes for V acuum Discharge- Tubes, of which the .following 'is a full, clear, and exact description, reference being had to the accompanying drawings.

This invention relates to X-ray tubes and other vacuum discharge apparatus, and more especially to the anodes or targets for such tubes. The essential requirements of these anodes are that they shall have a facing or receiving portion of highly refractory infusible metallic nature, and a backing of high heatconductivity and dissipating effect. tofore been met by employing fora target a button of refractory metal such as tungsten secured to or cast within the face of a massive block of silver or copper so as to utilize the high melting point of the former and the high conductivity of the latter. However, the shrinkage of silver or copper upon cooling places a great strain upon the tungsten button which being brittle, is sometimes found to crack or break; and in addition the tungsten unless previously compacted by mechanically working is liable to be porous o spongy, so as toabsorb the copper or other base metals with which it comes in contact. The base metal so absorbed possesses the power of occluding gases and hence seriously impairs the operation of the apparatus.

The objects of the present invention are the provisionof a new and improved anode which shall combine the infusibility of tungsten with the cheapness and the high heat conductivity of copper, and in which all difiiculty of interpenetration shall be overcome; the provision of a new and improved means for establishing thermal connection between the tungsten and the copper; the provision of new and improved means for shielding the refractory target from its base; while further objects and adyantages will become apparent as the descifiption proceeds.

ore specifically the present invention comprises certain improvements upon the invention set forth and claimed in the pat- These requirements have heremetal target is embraced within a thin shell of steel or other inert metal which will not itself penetrate the refractory metal and will shield it from the copper mass outside.

. Within the scope of my invention this steel shell may either be applied to the button and the 'two together thereafter cast into the copper backing, or the steel shell can first be cast into the copper backing and the refractory button thereafter secured therein by means of some suitable solder such as silver or a silver alloy.

In the drawings accompanying and forming a part of this application I have illustrated the steps of my improved method and the construction of my improved device. In these drawings Figure 1 represents a perspective view of a complete anode containing my improvements; Fig. 2 is a longitudinal sectional View of the same; Figs. 3, 4 and 5 are longitudinal sectional views showing successive steps in the construction of the same prior to the stage shown in Fig. 2; Fig. 6 is a perspective view of a button and its steel shell adapted for use in a modified form of the invention; and Fig. 7 is a longitudinal sectional view shown in Fig. 6.

According to the preferred form of my inof an anode cast about a button of the type I,

vention, a copper body 1 is cast about a hol- 1 low cylindrical steel shell 2 as shown in Fig. 3, leaving a portion of the walls of said shell projecting. After cleaning thoroughly the interior of said shell from dust, scale,

oxid, etc., by acids, scraping, or other means,

i a button 3 of silver or silver alloy or other suitable solder is inserted into said shell,

desired surface. The projection of the shell beyond the surface of the copper body prevents the molten silver from coming in contact with the copper, since it is well known that in the molten state the silver will dis solve copper very rapidly, and any material admixtureof copper with the silver will hurt the operation of the anode. However a small percentage of copper, for example ten per cent. or less, appears to be inocuous and is even preferred by me, since it depresses the melting point of the silver which, in its pure state, is inconveniently near the melting point of copper.

In Fig. 6 I have illustrated a modified form of my invention, in which the tungsten or other refractory button 4" is first inclosed in a shell or sheath 2 of steel, wrought iron, or the like material, and thereafter cast directly into the copper base 1*,

after which the projecting face of the button is ground and polished in the usual manner. So far as avoiding the absorption of copper is concerned thesecond embodiment is fully as satisfactory as the first, but the thermal contact established between the button and its backing appears not to be so perfect as in the former instance, this being possibly due partly to the oxidation of the tungsten at the high temperature obtained in the casting, and possibly to some oxidation of the iron at the same time.

While I have specifically mentioned tungsten as the material for'the button I do not limit myself thereto since other refractory metals like molybdenum or osmium could be used for the target; also I do not restrict myself to a steel or iron shell, since other materials can be used in case they. are not volatile or occluding or of a nature to alloy with copper or silver or to penetrate tungsten and possess a higher melting point than copper,,e. g. platinum or gold. Also while I have particularly suggested silver or silver solder I do.n0t restrict myself to such material since other alloys can be used in case they have a melting point less than that of the other members, make good thermal contact, and are non-occluding. Preferably they should not penetrate the tungsten, al-

though penetration in the case of silver or any other matrix might be unobjectionable in case the metal were non-occluding.

Having thus described my invention,

what I claim is p 1. An anode for vacuum tubes comprising a massive. copper body cast around a hol-' low shield of inert metal as steel, and a target of refractory metal located inside said shield and held in thermal contact with the walls thereof.

2. An anode fordischarge tubes comprising a massive copper base, a tungsten target located in a cavity formed in said base, and a thin iron shield interposed between the tungsten and copper.

' 3. An anode for discharge tubes comprising a hollow iron shield, a copper body cast around said shield, and a target'of refractory metal located in said shield and soldercd thereto.

4. A blank for an anode comprising a hollow iron shell cast Within a massive copper body.

5. A blank for anodes for discharge tubes comprising a'hollow shell cast within a body of heat conducting and dissipating metal, a target of refractory metal located within said shell, .and a button of more fusible metal located beneath said target.

6. A blank for anodes for discharge tubes comprising a hollow iron shell cast within a massive copper body, a tungsten target located Within said shell, and a silver matrix surrounding said target and engaging the Walls'of said shell, the walls of said shell projecting outwardly beyond the face of said copper body. 7. An anodefor discharge tubes comprismg a tungsten button and an iron shell embracing the same.

In testimony whereof, I hereunto aflix my signature in' the presence of two witnesses. CHARLES FREDERICK WILLIAM BATES. Witnesses:

HAROLD E. SMITH, GLADYS YFROMANT. 

